The present invention relates generally to caches, and more particularly to allocation of texture data to a cache in a graphics processing system.
Graphics processing systems generate graphics for display on video monitors and the like. The graphics are often extremely detailed, and provide realistic views of three dimensional images on two dimensional displays. A variety of techniques are utilized to increase the realism of displays. For example, graphics processing systems often determine what objects should be displayed based on a supposed eye point of an observer, as well as the relative sizes of the objects. In addition, one technique widely used to increase realism of a display is the use of textures. Textures indicate surface qualities of an object. The surface qualities may be variations in color, as well as variations in the physical surface of the object.
Textures are often stored in the form of texture maps which are often defined with respect to a surface. More specifically, texture maps are often defined with respect to types of surfaces, as well as the level of detail of the surfaces. In addition, much as a surface of a video screen is comprised of pixels, texture maps are comprised of texture elements, or texels. As the number of surfaces displayed during the course of execution of an application are often very large, and details of the surfaces complex, the size of the texture maps, and therefore the number of texels, may be large.
Texels are used in conjunction with geometric information of an object to determine color and intensity of a pixel displayed on a display device. Often multiple texels from a single texture map are used, or blended, to determine the display characteristics of a pixel. In addition, at times texels from more than one texture map are used to determine the display characteristics of any one pixel. Therefore, color and intensity of a single pixel may be formed through blending multiple texels, and these texels may come from more than one texture map.
Graphics processing systems, therefore, require access to large numbers of texels to form realistic displays. This data is generally stored within a computer system memory. Accessing computer system memory, however, is often a relatively lengthy process and may produce delays which could degrade the realism of generated displays.
A graphics cache dedicated to storing graphics data is sometimes used to enhance accessibility of graphics data by a graphics processing system. The graphics cache is provided graphics data from the system memory prior to a demand by the graphics processing system. The graphics system, therefore, has graphics data available for use when desired, thereby reducing the need to promptly access system memory and reducing problems associated with memory latency.
Preferably, data for use by the graphics processing system is available for use by the graphics processing system when needed. This maximizes cache usage and reduces cache swapping and texture map fetching, thereby increasing graphics processing system performance. Texture maps are often quite large, however, and without sufficient care in providing texture map data to the graphics cache, less than optimum usage of the graphics cache may result. Moreover, during operation of the graphics processing system demands for various texture maps may dynamically vary.
The present invention therefore provides dynamic allocation of texture map memory. In one embodiment, the present invention comprises a graphics processing system. A graphics processing system includes a cache adapted to receive data from a system memory. The cache is partitioned into a plurality of slots. The graphics processing system additionally includes a register containing information regarding data provided to the slots. In a further embodiment the cache comprises a plurality of cache lines and the slots are comprised of a plurality of cache lines. Further, the data stored in the cache comprises texture maps, with a maximum of one texture map stored in any one slot.
In another embodiment, the present invention comprises a method of performing graphics processing. The method includes partitioning a cache into a plurality of slots, and dynamically allocating the plurality of slots. The register is updated with slot allocation status. In another embodiment the slots are allocated after determining the number of texture maps needed to render a scene. In another embodiment slots are divided equally among texture maps. In yet another embodiment in a graphics processing system having a cache memory used for storage of texture data, the invention comprises a method of dynamically allocating cache memory. The method includes partitioning the cache into a plurality of slots and determining the number of texture blocks to be rendered. The plurality of slots are allocated among the texture blocks.
Many of the attendant features of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description considered in connection with the accompanying drawings.